Method and means for etching figures on rollers



Jan. 27, 1959 R. KAUSCHKA 2,870,560

METHOD AND MEANS FOR ETCHING FIGURES ON ROLLERS Filed Feb. 1. 1956 HIS ATTORNEY METHOD AND MEANS FOR ETCHIYG FIGURES ON ROLLERS Richard Kauschka, Kufstein, Austria, assignor to Roehlen Engraving Works, Inc., Rochester, N. Y., a corporation of New York Application February 1, 1956, Serial No. 562,858

Claims priority, application Austria February 3, 1955 6 Claims. (Cl. 41-9) In order to etch figures or patterns according to the conventional methods, the roller is coated with a hard coating that is resistant to the etching medium. The figures are scratched into this coating in the form of thin lines, or the coating is interrupted from the outset by a photochemical process so as to show the figure. The roller is then made to run in the etching bath and the etching medium corrodes the uncoated parts of the surface of the roller,

Due to the fact that the etching medium acts in all directions, although not uniformly at all, the contours are widened while they are being deepened. The proportion of deepening to widening depends not only on the etching medium, but also in the direction of the contours in relation to the direction of rotation. Transverse contours are affected in a different manner than longitudinal ones. Another factor to be considered is that the material of the rollers is usually not completely homogeneous causing some places to be more strongly affected by the etching medium than others. All irregularities resulting from the above-mentioned causes and which cannot be overcome by the engraver, lower the quality of the engraving.

Consequently, in the case of delicate patterns it was still necessary to use the method of impressing the pattern on the roller and to accept the disadvantages inherent in this method, which calls for the cold forming of the roller material, which causes a deterioration of its structure and diminishe its power of resistance. The process requires great mechanical forces; the material which is piled up has to be removed by grinding off or in a similar manner. This method is very time consuming. In order to accelerate the operation during the impression, intermediate etchings are sometimes carried out, which remove a part of the material which otherwise would have to be formed by impression.

The roller is prepared for such intermediate etchings by putting an easily moldable mass, resistant to the etching medium, in the free angle, formed by the negative roller with the roller to be engraved, on the entering side. When the rollers are rotated they form a film from this mass on the roller to be etched, except at those places at which the rollers touch. The excess mass is blown away by means of compressed air, so that there remains no seam, if possible. The roller to be etched is then removed from the impressing apparatus. The uncoated portions are now etched in an etching device. However, the etched profile has another character than the impressed one, for the etching also spreads sideways while the impression only acts in depth. Consequently, only a little etching'can be done at any one time; the roller must always be newly coated in the impression device. The old coating and the acid must be washed oif every time. At the end, a strong impression is necessary in order to remove, as far as possible, the defective etchings, by cold formingof the roller material. The long drawn out process of changing from impressing to etch- 7 2,870,560 Patented Jan. 27, 1959 is still necessary and which unfavorably affects the roller material, are the disadvantages of this method.

The process of this invention overcomes the abovedescribed defects and disadvantages. The recesses in the roller to be etched completely fit into the elevations on the negative roller, or vice versa. The etching process itself becomes considerably more effective by the continuous removal of the laminated layer of spent etching media; the deep etching takes place in a single operation and in a fraction of the time required in the past. The material is no longer adversely afiected but retains its structure and power of resistance, and the engravings become completely uniform even in non-homogeneous material.

In order to explain the process, the drawing shows diagrammatically an example of an apparatus or device in its simplest form, which permits the realization of the invention.

Fig. l is a schematic elevation, partly in section, showing the device at the start;

Fig. 2 is a similar view of the same parts at the end of the etching process; and

Fig. 3 is an enlarged, fragmentary view of portions of the apparatus in the position shown in Fig. 2 and showing more clearly the interrelation of the pattern roller and the etched roller at the end of the etching process.

The negative roller 1, which determines the pattern, with the recesses 2 indicated thereon, touches with the elevations of its jacket surface 3 the roller 4 that is to be engraved. The rollers 1 and 4 rotate in opposite directions under slight pressure against eachother and are connected by means of cog Wheels, whose gear ratio corresponds to the numbers of the figures on the circumferences of the rollers. If rollers of ditierent sizes are to be engraved with negative rollers of different sizes, the simple gear transmission is replaced by a change speed gear.

The free angle on the entering side, which is formed between the rollers 1 and 4, is filled with a body of easily moldable plastic mass 5 that is resistant to the etching medium. From this supply the rollers 1 and 4 carry along a film which, however, only forms on those places, such as the elevations 6 of roller 4, at which the rollers do not yet touch each other. The points of contact thus remain free from coating. When the roller 4 passes through the etching medium 7 in the container 8, it acts on those places which have no coating. Roller 4 ha trunnions 4a supported in bearing 4b on the walls of container 8.

The supply of the mass 5 completely squeezes off the layer of spent etching medium and products, a new coating mass 5 is formed which is interrupted according to the new points of contact of the rollers. Thus, the etching process progresses rapidly and continuously, corresponding exactly to the form of the negative roller 1. When coated places are no longer formed, the depth of etching has been reached, and, if the etching process is not stopped, the diameter of the etched roller diminishes. For the purpose of limiting the depth of etching, the invention provides adjustable stops 9, which have the additional purpose of preventing the negative roller 1 from sinking in and thereby from drawing wrongly when its surface is interrupted. Stops 9 arrest the descent of arms 10 which are pivoted at one end, as at 11 to a suitable support. The other ends of arms 10 are provided with bearings (not shown) in which are journaled the trunnions 1a of roller 1. Screws 12 are supported by any suitable means indicated at 13 for pressing roller 1 against roller 4 and such supporting means may be movably 3 mounted and spring actuated by any suitable means not shown and well understood in the art.

When the operation is completed, the supporting arms 10 are brought to rest against the stops 9 (Fig. 2) thereby preventing the negative roller 1 from sinking in any further, the jacket surface of the roller 4- has taken on exactly the complementary form of the roller It, and an extremely thin protective coating has formed on the rollers. This completes the etching process; the etching medium in the container 8 is replaced by water which rinses and cleanses the roller 4.

It will thus be seen that the invention accomplishes its objects and while it has been herein disclosed by reference to the details of'a preferred embodiment, it is to be understood that such disclosure is intended in an i n trative, rather than a limiting sense, as it contcm ate .i that various modifications in the construction arrangement of the parts will readily occur to those skilled in the art, within the spirit of the invention and the scope of the appended claims.

I claim:

1. The method of etching patterns on roller comprising the steps of rotating a pattern-carrying roller and a roller to be etched in pressing contact with each other at the same surface speed, positioning in the entrant angle between said rollers a body of moldable plastic material inert to the etching fluid for continuously coating therewith the non-contacting surface portions of the roller to be etched, and simultaneously rotating the surface of the roller to be etched through an etching fluid while being coated with said material and pressed in contact with said pattern roller.

2. The method as specified in claim 1 in which the spent products of said etching fluid on said roller to be etched are continuously squeezed oil and removed by the contact of said coating material with said roller during the rotation thereof.

3. The method as specified in claim 1 in which said it roller to be etched is simultaneously and continuously coated with said inert material, subjected to the action of said etching fluid and cleaned of the spent products of said fluid during the rotation of said roller.

4. An apparatus for etching patterns on rollers comprising a container for etching fluid; means rotatably supporting a roller to be etched in fixed relation to said container with a portion of said roller dipping below and a portion of said roller rising above the etching fluid contained in said container; a pattern 'roller having raised portions forming the negative of the pattern to be etched on said first-mentioned roller; means rotatably mounting said pattern roller for movement towardand away from said roller to be etched; and means urging said pattern roller into rolling contact with a portion of said roller to be etched above the etching fluid in said container, the arrangement being such that when said pattern roller and said roller to be etched are continuously rotating in opposite directions in rolling contact, moldable etching-fluid-inert plastic material positioned in the entry angle between said rollers continuously coats the non-contacting surface portions of the roller to be etched and the non-coated portions of the roller tobe etched are etched away as they pass through the etching fluid.

5. The apparatus of claim 4 having adjustable stop means for limiting the movement of said pattern roller toward said roller to be etched when the desired depth of etching has been reached.

6. The apparatus of claim 5 in which said means rotatably supporting said roller to be etched comprises bearings mounting on opposed walls of said container.

References Cited in the file of this patent UNITED STATES PATENTS Ofienbacher Sept. 3, 1901 

